Mihalik, 50, was shot and killed outside Reddam House Primary, where he had dropped off his eight-year-old son on Tuesday morning.
The boy was injured in the attack.
Police confirmed they had taken in a suspect for questioning.
“This office can confirm that a suspect is being questioned by detectives of the anti-gang unit in connection with the murder of a 50-year old man this morning in Green Point,” police spokesperson Noloyiso Rwexana said.
Sources have confirmed the suspect was nabbed close to the scene of the shooting, and less than two hours after it occurred.
Advocate Janos Mihalik, Pete’s father, said: “I am aware that a suspect has been taken in for questioning.
“Currently I am at the hospital with Pete’s son. He’s going to be fine. Fortunately it’s not serious.”
Provincial Health Department spokesperson Bianca Gilbert confirmed the slain lawyer’s son was admitted to the New Somerset Hospital after sustaining a gunshot wound.
“The patient was stabilised and transferred to another health-care facility for further medical treatment,” she said.
Janos Mihalik said he was concerned about his son’s eldest daughter.
“My granddaughter is busy writing her matric exams,” he said.
Reddam House Primary was placed under temporary lockdown after on Tuesday’s shooting.
“Our staff have been proactive and the school is under lockdown.
“Fidelity, our security company, is busy dispensing extra security and guarding,” the school said.
“We will keep it so for the rest of the day as we work together to get through this extremely traumatic time for everyone,” head of ELS and Preparatory Shirley Oosthuizen said.
The school said it kept children inside their classrooms while the body of Mihalik was being removed.
Oosthuizen said the school’s director Sheena Crawford-Kempster, specialist support staff and extra councillors met for a debriefing.
Mihalik’s clients included alleged Sexy Boys gang boss Jerome “Donkie” Booysen, alleged nightclub security kingpin Mark Lifman and suspected 28s gang boss Ralph Stanfield.
Stanfield was recently released on bail after spending a weekend behind bars when police raided his garage and found cars allegedly stolen.
He was representing former Sotheby’s boss Jason Rohde, who is accused of murdering his wife Susan.
His father has represented a number of alleged criminal bigwigs including former 28s boss George “Geweld” Thomas and Quinton “Mr Big” Marinus.
Community Safety MEC Dan Plato said: “This brazen disregard for life and the rule of law is extremely worrying as it exposes the truth about the rampant Cape Town underworld, bubbling underneath the veneer of SAPS’s anti-gang efforts.”
On Friday, the much anticipated Anti-Gang Unit is expected to be launched, however, Plato said it could be too little too late for the unit with 808 of all gang-related murders in the country occurring in the province.
“While any additional resources are welcomed to help address the high levels of crime, specifically violent interpersonal crime, the families of the hundreds who died last year alone at the hands of gangsters and druglords need to be assured the police are the ones in control of law and order.”
The Green Point Ratepayers Association said they were deeply concerned by the shooting. Chairperson Jenny McQueen said: “We are deeply shocked and extremely sad by this shooting. I don’t think anyone could’ve prevented it. I have no doubt that this was a hit on him. We extend our deepest condolences to the family during this time.”
* Additional reporting by IOL@MarvinCharles17